Measurement instrument, measurement method, measurement system, and program

ABSTRACT

An acquisition unit acquires at least one of the vertical-direction acceleration and the width-direction acceleration of a surface of a structure on which a moving object moves from an acceleration sensor provided in the structure on which the moving object moves. An analysis unit analyzes the motion of the moving object moving on the structure on the basis of at least one of the vertical-direction acceleration and the width-direction acceleration.

BACKGROUND

1. Technical Field

The present invention relates to a measurement instrument, a measurementmethod, a measurement system, and a program.

2. Related Art

JP-A-2005-30786 describes that, in measurement units of the weights ofvehicles passing through bridges, the running speeds of passing vehiclesare detected by installing multiple sensors for speed detection alongrunning paths, the wheel axis locations and the number of wheel axes ofpassing vehicles are detected by installing sensors for wheel axisdetection in running paths, passing vehicles are recognized usingrunning speeds and wheel axis locations, the deformation amounts ofbridges are measured multiple times within set measurement durations forthe wheel axes of at least the passing vehicles that have beenrecognized by installing measurement units of deformation amounts in thebridges, and the weights of the passing vehicles are computed on thebasis of vehicle recognition data and the measurement data of thedeformation amounts for wheel axes.

In JP-A-2005-30786, the speeds or weights of vehicles running on bridgesare measured and vehicles are recognized using sensors for speeddetection, sensors for wheel axis detection, and distortion gauges.Therefore, in JP-A-2005-30786, a number of kinds of sensors are used,and thus there is a problem in that high costs are required and greatefforts are taken for installation of sensors and the like.

SUMMARY

An advantage of some aspects of the invention is to analyze the motionof moving objects on structures using small-size and simple systemconstitutions and reduce costs or save efforts for installation ofsensors.

A first aspect of the invention is directed to a measurement instrumentincluding: an acquisition unit that acquires width-directionacceleration of a surface of a structure on which a moving object movesfrom an acceleration sensor provided in the structure on which themoving object moves; and an analysis unit that analyzes motion of themoving object moving on the structure on the basis of thewidth-direction acceleration. According to the first aspect, it ispossible to analyze the motion of moving objects on structures usingsmall-size and simple system constitutions and reduce costs or saveefforts for installation of sensors.

The acceleration sensor may be provided in an end portion of thestructure which is parallel to a regulation direction of a movingdirection regulation unit for the moving object which is provided in thestructure and in a central portion of the end portion in the regulationdirection. In such a case, the acceleration sensor is capable of clearlydetecting width-direction acceleration.

The acquisition unit may have a displacement computation unit thatacquires vertical-direction acceleration of the surface of the structureon which the moving object moves and computes vertical-directiondisplacement of the structure on the basis of the vertical-directionacceleration, and the analysis unit may compute a passing duration ofthe moving object moving on the structure on the basis of thevertical-direction displacement. In such a case, the measurementinstrument is capable of computing the passing duration of movingobjects on structures using small-size and simple system constitutionsand is capable of reducing costs or saving efforts for installation ofsensors.

The analysis unit may compute a passing duration of the moving object onthe basis of the wave amplitude of the vertical-direction displacementgenerated due to movement of the moving object on the structure. In sucha case, the measurement instrument becomes capable of accuratelycomputing the passing durations of moving objects.

The analysis unit may divide the wave amplitude into multiple sectionsand compute the passing duration of the moving object moving on thestructure which corresponds to each of the sections. In such a case, themeasurement instrument becomes capable of computing the passingdurations of moving objects on structures in detail.

The acquisition unit may have a displacement computation unit whichacquires the vertical-direction acceleration of the surface of thestructure on which the moving object moves and computes thevertical-direction displacement of the structure on the basis of thevertical-direction acceleration, and the analysis unit may determinestoppage of the moving object on the structure on the basis of thewidth-direction acceleration and the vertical-direction displacement. Insuch a case, the measurement instrument is capable of determining thestoppage of moving objects on structures using small-size and simplesystem constitutions and is capable of reducing costs or saving effortsfor installation of sensors.

The analysis unit may determine stoppage of the moving object on thestructure on the basis of a wave amplitude of the width-directionacceleration generated due to movement of the moving object on thestructure and a wave amplitude of the vertical-direction displacementgenerated due to movement of the moving object on the structure. In sucha case, the measurement instrument becomes capable of accuratelycomputing the stoppage of moving objects.

The analysis unit may determine stoppage of the moving object in a casein which the wave amplitude of the width-direction acceleration islarger by a predetermined value than the wave amplitude of thevertical-direction acceleration. In such a case, the measurementinstrument becomes capable of accurately computing the stoppage ofmoving objects.

The analysis unit may compute a stoppage time of the moving object onthe structure on the basis of a peak time of the vertical-directiondisplacement and a time at which the wave amplitude of thewidth-direction acceleration is terminated. In such a case, themeasurement instrument is capable of computing the stoppage time ofmoving objects on structures using small-size and simple systemconstitutions and is capable of reducing costs or saving efforts forinstallation of sensors.

The analysis unit may determine path changes of the moving object on thestructure on the basis of the width-direction acceleration. In such acase, the measurement instrument is capable of determining path changesof moving objects on structures using small-size and simple systemconstitutions and is capable of reducing costs or saving efforts forinstallation of sensors.

The analysis unit may determine path changes of the moving object on thebasis of a degree and a sign of a crest value of the width-directionacceleration. In such a case, the measurement instrument becomes capableof accurately determining the path changes of moving objects.

The analysis unit may determine an entering direction of the movingobject into the structure on the basis of the width-directionacceleration and an envelope curve of the width-direction acceleration.In such a case, the measurement instrument is capable of determining theentering direction of moving objects on structures using small-size andsimple system constitutions and is capable of reducing costs or savingefforts for installation of sensors.

The analysis unit may determine the entering direction of the movingobject on the basis of the appearance time of the envelope curve withrespect to the width-direction acceleration. In such a case, themeasurement instrument becomes capable of accurately determining theentering direction of moving objects.

The analysis unit may determine the entering direction of the movingobject on the basis of whether the envelope curve appears even beforethe width-direction acceleration appears or the envelope curve appearseven after the width-direction acceleration does not appear any longer.In such a case, the measurement instrument is capable of accuratelydetermining the entering directions of moving objects.

A filter unit that suppresses acceleration components which are includedin the width-direction acceleration that is computed by the envelopecurve and is generated due to movement of the moving object on thestructure may be further provided. In such a case, the measurementinstrument is capable of accurately determining the entering directionsof moving objects.

An acceleration waveform acquisition unit that acquires and storescharacteristic information of a waveform of the width-directionacceleration may be further provided. In such a case, the measurementinstrument is capable of reducing the storage capacities of storagedevices.

The analysis unit may have a displacement computation unit that acquiresvertical-direction acceleration of a surface of the structure on whichthe moving object moves and computes vertical-direction displacement ofthe structure on the basis of the vertical-direction acceleration and adisplacement waveform acquisition unit that acquires and storescharacteristic information of a waveform of the vertical-directiondisplacement. In such a case, the measurement instrument is capable ofreducing the storage capacities of storage devices.

An output unit that outputs analysis results of motion of the movingobject may be further provided. In such a case, users are able to learnthe analysis results of the motion of moving objects.

A filter unit that suppresses intrinsic resonance frequency componentswhich are included in the width-direction acceleration and which thestructure has may be further provided. In such a case, the measurementinstrument is capable of accurately analyzing the motion of movingobjects on structures.

The structure may be a bridge. In such a case, the measurementinstrument is capable of analyzing motion of moving objects on bridgesusing small-size and simple system constitutions and is capable ofreducing costs or saving efforts for installation of sensors.

The width-direction acceleration may be a component of an accelerationof gravity due to a slope of the structure. In such a case, themeasurement instrument is capable of accurately analyzing the motion ofmoving objects on structures.

The analysis unit may compute a passing duration of the moving objectmoving on the structure on the basis of the width-directionacceleration. In such a case, the measurement instrument becomes capableof accurately computing the passing durations of moving objects.

A second aspect of the invention is directed to a measurement methodincluding: acquiring width-direction acceleration from an accelerationsensor provided in a structure on which a moving object moves; andanalyzing motion of the moving object moving on the structure on thebasis of the width-direction acceleration. According to the secondaspect, it is possible to analyze the motion of moving objects onstructures using small-size and simple system constitutions and reducecosts or save efforts for installation of sensors.

A third aspect of the invention is directed to a measurement systemincluding: an acceleration sensor provided in a structure on which amoving object moves; an acquisition unit that acquires width-directionacceleration that is output from the acceleration sensor; and ananalysis unit that analyzes motion of the moving object moving on thestructure on the basis of the width-direction acceleration. According tothe third aspect, it is possible to analyze the motion of moving objectson structures using small-size and simple system constitutions andreduce costs or save efforts for installation of sensors.

A fourth aspect of the invention is directed to a program commanding ameasurement instrument to execute a sequence, the sequence includingacquiring width-direction acceleration from an acceleration sensorprovided in a structure on which a moving object moves; and analyzingmotion of the moving object moving on the structure on the basis of thewidth-direction acceleration. According to the fourth aspect, it ispossible to analyze the motion of moving objects on structures usingsmall-size and simple system constitutions and reduce costs or saveefforts for installation of sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a view illustrating a constitutional example of a measurementsystem according to a first embodiment.

FIG. 2 is a view illustrating an example of an installation method of anacceleration sensor.

FIG. 3 is a view illustrating an example of a fashion of deformation ofa floor slab.

FIG. 4 is a view illustrating a constitutional example of functionalblocks of a measurement instrument.

FIG. 5 is a view illustrating relationships between vertical-directionacceleration and width-direction acceleration which are acquired usingan acquisition unit and processes executed on the basis of theacceleration.

FIG. 6 is a view illustrating an example of an envelope curve.

FIG. 7 is a view illustrating an example of frequency characteristics ofacceleration when a vehicle passes through a floor slab.

FIG. 8 is a first view illustrating the width-direction acceleration andthe vertical-direction displacement of a floor slab which are generatedby the passing of a vehicle.

FIG. 9 is a second view illustrating the width-direction accelerationand the vertical-direction displacement of a floor slab which aregenerated by the passing of a vehicle.

FIG. 10 is a first view illustrating the passing duration of a vehicle.

FIG. 11 is a second view illustrating the passing duration of a vehicle.

FIG. 12 is a view illustrating an example of width-directionacceleration and vertical-direction displacement in a case in which avehicle passes through on a floor slab without stopping.

FIG. 13 is a view illustrating an example of width-directionacceleration and vertical-direction displacement in a case in which avehicle stops on a floor slab.

FIG. 14 is a first view illustrating a path change of a vehicle on afloor slab.

FIG. 15 is a view illustrating a change in the width-directionacceleration during the path change of a vehicle in FIG. 14.

FIG. 16 is a second view illustrating a path change of a vehicle on afloor slab.

FIG. 17 is a view illustrating a change in the width-directionacceleration during the path change of a vehicle in FIG. 16.

FIG. 18 is a view illustrating the entering direction of a vehicle intoa floor slab.

FIG. 19 is a view illustrating width-direction acceleration and anenvelope curve thereof in a case in which a vehicle directly enters afloor slab on which an acceleration sensor is mounted.

FIG. 20 is a view illustrating width-direction acceleration and anenvelope curve thereof in a case in which a vehicle enters from anadjacent floor slab on which an acceleration sensor is not mounted.

FIG. 21 is a flowchart illustrating an operation example of themeasurement instrument.

FIG. 22 is a view illustrating an example of functional blocks of ameasurement instrument according to a second embodiment.

FIG. 23 is a view illustrating characteristic information ofwidth-direction acceleration and restoration of the width-directionacceleration from the characteristic information.

FIG. 24 is a view illustrating characteristic information ofvertical-direction displacement and restoration of thevertical-direction displacement from the characteristic information.

FIG. 25 is a view illustrating travelling-direction acceleration of afloor slab according to a third embodiment.

FIG. 26 is a view illustrating a temporal change of travelling-directionacceleration.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The invention will be described with reference to the accompanyingdrawings.

First Embodiment

FIG. 1 is a view illustrating a constitutional example of a measurementsystem according to a first embodiment. As illustrated in FIG. 1, themeasurement system has a measurement instrument 1 and an accelerationsensor 2. In addition, FIG. 1 illustrates a bridge 4.

The bridge 4 has a bridge pier 4 a located in the central portion(including substantial central portions) of the bridge 4, two bridgeabutments 4 b and 4 c located at both ends, a floor slab 4 d extendingfrom the bridge abutment 4 b to the bridge pier 4 a, and a floor slab 4e extending from the bridge abutment 4 c to the bridge pier 4 a. Thebridge pier 4 a and the bridge abutments 4 b and 4 c are respectivelyfixed onto basements (not illustrated) constructed on the ground.

The acceleration sensor 2 is preferably provided on the floor slab 4 dof the bridge 4 in a case in which the subject structure is the bridge4. Here, the floor slab 4 d refers to a portion constituting a surfaceon which moving objects move. The acceleration sensor 2 is installed,for example, on a side surface of the floor slab 4 d. The accelerationsensor 2 measures acceleration generated by the deformation of the floorslab 4 d which is caused by a vehicle 5 (corresponding to a movingobject according to the invention) passing through the bridge andoutputs acceleration data thereof. The measurement instrument 1 and theacceleration sensor 2 are connected to each other through acommunication network 3 so as to be capable of communicating with eachother, and the acceleration sensor 2 sends the measured accelerationdata to the measurement instrument 1 through the communication network3. The acceleration sensor 2 includes an inertia sensor that outputsacceleration and angular speeds. Hereinafter, in some cases,acceleration data that are output from the acceleration sensor 2 will beexpressed simply as acceleration.

The acceleration sensor 2 has, for example, a wireless communicationinterface or is connected to a wireless communication interface so as tobe connected to the communication network 3 through the wirelesscommunication interface.

The measurement instrument 1 receives the acceleration sent from theacceleration sensor 2. The measurement instrument 1 detects the passingof the vehicle 5 on the floor slab 4 d on the basis of the accelerationsent from the acceleration sensor 2. That is, the measurement instrument1 detects whether or not the vehicle 5 passes through on the floor slab4 d. Hereinafter, the passing of the vehicle 5 on the floor slab 4 dwill be referred to as an “event”.

When an event is detected, the measurement instrument 1 analyzes themotion of the vehicle 5 that has passed through the floor slab 4 d. Forexample, the measurement instrument 1 analyzes the passing duration,stoppage on the floor slab 4 d, path changes, entering direction, andthe like of the vehicle 5 that has passed through the floor slab 4 d.

As described above, the measurement instrument 1 detects events on thebasis of acceleration obtained from the acceleration sensor 2 andanalyzes the motion of the vehicle 5. Therefore, the measurementinstrument 1 does not need to use a variety of sensors in order toanalyze the motion of the vehicle 5 and is capable of reducing costs. Inaddition, the measurement instrument 1 is capable of analyzing themotion of the vehicle 5 using at least one acceleration sensor 2 andsaves efforts for the installation of sensors on the floor slab 4 d.

FIG. 2 is a view illustrating an example of an installation method ofthe acceleration sensor 2. FIG. 2 illustrates a perspective view of thefloor slabs 4 d and 4 e illustrated in FIG. 1.

FIG. 2 illustrates main beams 4 f to 4 i which are not illustrated inFIG. 1. The main beams 4 f to 4 i are overlaid on the upper portions ofthe bridge pier 4 a and the bridge abutments 4 b and 4 c, and the floorslabs 4 d and 4 e are installed on the upper portions of the main beams4 f to 4 i. Hereinafter, in order to facilitate the understanding ofdescription, the road surface of the floor slab 4 d is considered to behorizontal, and the vertical direction of the road surface coincideswith the perpendicular direction.

The acceleration sensor 2 is provided in the central portion of a side(end portion) that is substantially parallel to the regulation directionof a moving direction regulation unit for the moving object which isprovided in the structure having a substantially quadrilateral shapewhen seen in a plan view. For example, the acceleration sensor 2 ismounted in the central portion (including substantial central portions)in the regulation direction of a side surface 4 da (corresponding to theend portion according to the invention) that is parallel to (orsubstantially parallel to) the regulation direction of the movingdirection regulation unit (for example, traffic lanes, curbstones,parapets, and the like) for the vehicle 5 which is provided on the floorslab 4 d. The acceleration sensor 2 is capable of measuring accelerationgenerated in each of three-axis directions that intersect with eachother. The acceleration sensor 2 is installed on the side surface 4 daof the floor slab 4 d by aligning, among three detection axes (an xaxis, a y axis, and a z axis), one axis (for example, the x axis) to thevertical direction of the road surface of the floor slab 4 d andaligning another axis (for example, the z axis) to the width directionof the road surface of the floor slab 4 d. The acceleration sensor 2detects acceleration along the three axes at, for example, set samplingfrequencies and sends the detected acceleration data to the measurementinstrument 1 through the communication network 3.

FIG. 3 is a view illustrating an example of a fashion of the deformationof the floor slab 4 d. FIG. 3 illustrates a perspective view of thefloor slab 4 d of FIG. 2 cut at the portion of the acceleration sensor2.

As illustrated in FIG. 3, in a case in which the vehicle 5 passesthrough on the floor slab, the floor slab 4 d deforms to bend downwardsdue to the load L of the vehicle 5. A mounting location 2P of theacceleration sensor 2 is a location farthest from the bridge pier 4 aand the bridge abutment 4 b, and thus the location of the floor slab 4 din the vertical direction (the location along the x axis) is likely tochange more significantly than other locations. In addition, themounting location 2P of the acceleration sensor 2 is on the side surface4 da of the floor slab 4 d, and thus the slope of the floor slab 4 dwith respect to the horizontal direction (the slop of the z axis) islikely to be more significant than that in other locations. Therefore,when the acceleration sensor is mounted at the mounting location 2P ofthe floor slab 4 d, the acceleration sensor 2 is capable of clearlydetecting acceleration in the vertical direction or acceleration in thewidth direction of the floor slab 4 d which is generated by the passingof the vehicle 5.

FIG. 4 is a view illustrating a constitutional example of the functionalblocks of the measurement instrument 1. As illustrated in FIG. 4, themeasurement instrument 1 has a control unit 11, a communication unit 12,a storage unit 13, a display unit (corresponding to an output unitaccording to the invention) 14, and an operation unit 15.

Although described below in detail, the control unit 11 detects events.When detecting an event, the control unit 11 analyzes the motion of thevehicle 5 that has passed through on the floor slab 4 d.

The communication unit 12 receives acceleration from the accelerationsensor 2 through the communication network 3. The communication unit 12outputs the acceleration received from the acceleration sensor 2 to thecontrol unit 11.

The storage unit 13 stores programs, data, and the like necessary forthe control unit 11 to execute computation processes or controlprocesses. In addition, the storage unit 13 stores programs, data, andthe like necessary for the control unit 11 to realize predeterminedapplication functions. A variety of programs, data, and the like may bestored in non-volatile storage media in advance or may be received bythe control unit 11 from servers through the communication network 3 andstored in the storage unit 13. The storage unit 13 is constituted of,for example, a variety of integrated circuit (IC) memories such as readonly memory (ROM), flash ROM, and random access memory (RAM), recordingmedia such as hard discs and memory cards, or the like.

The display unit 14 outputs control results and the like of the controlunit 11 to a display device.

The operation unit 15 acquires operation data from users and executesprocesses of sending the operation data to the control unit 11.

The control unit 11 has an acquisition unit 21, an event detection unit22, an intrinsic resonance-blocking filter unit 23, a displacementcomputation unit 24, a vehicle component-blocking filter unit 25, and ananalysis unit 26. The respective units in the control unit 11 havefunctions that are realized using, for example, central processing units(CPU) that execute programs stored in the storage unit 13. Therespective units in the control unit 11 may have functions that arerealized using custom integrated circuits (IC) such as applicationspecific integrated circuits (ASIC) or may have functions that arerealized using CPU and ASIC.

The acquisition unit 21 acquires the acceleration of the accelerationsensor 2 which has been sent using the communication unit 12. Theacceleration acquired using the acquisition unit 21 includes at leastvertical-direction acceleration (x-axis direction acceleration) andwidth-direction acceleration (z-axis direction acceleration). Thevertical-direction acceleration and the width-direction acceleration areoutput to the respective units in the control unit 11, and predeterminedprocesses are executed.

FIG. 5 is a view illustrating relationships between thevertical-direction acceleration and the width-direction accelerationwhich have been acquired using the acquisition unit 21 and processesexecuted on the basis of the acceleration. As indicated by the block BL1in FIG. 5, for the vertical-direction acceleration a_(v) acquired usingthe acquisition unit 21, an envelope curve is computed. The envelopecurve of the vertical-direction acceleration a_(v) is used to detectevents as indicated by the block BL2. The envelope curve computationindicated by the block BL1 and the event detection indicated by theblock BL2 are executed using the event detection unit 22 describedbelow.

As indicated by the block BL11, for the vertical-direction accelerationa_(v) acquired using the acquisition unit 21, high-frequency componentsare suppressed. The vertical-direction acceleration a_(v) for whichhigh-frequency components are suppressed is used to compute displacement(the displacement of the floor slab 4 d in the vertical direction) asindicated by the block BL12. Vertical-direction displacement is computedby, for example, integrating the vertical-direction acceleration a_(v)twice. The suppression of high-frequency components of thevertical-direction acceleration a_(v) indicated by the block BL11 isexecuted using the intrinsic resonance-blocking filter unit 23 describedbelow, and the displacement computation indicated by the block BL12 isexecuted using the displacement computation unit 24 described below.

As indicated by the block BL13, for the width-direction accelerationa_(w) acquired using the acquisition unit 21, high-frequency componentsare suppressed. The suppression of high-frequency components of thewidth-direction acceleration a_(w) indicated by the block BL13 isexecuted using the intrinsic resonance-blocking filter unit 23 describedbelow.

As indicated by the block BL14, for the width-direction accelerationa_(w) acquired using the acquisition unit 21, low-frequency componentsare suppressed. The suppression of low-frequency components of thewidth-direction acceleration a_(w) indicated by the block BL14 isexecuted using the vehicle component-blocking filter unit 25 describedbelow.

As indicated by the block BL20, the vertical-direction displacement(BL12) computed from the vertical-direction acceleration a_(v) for whichhigh-frequency components are suppressed, the width-directionacceleration a_(w) for which high-frequency components are suppressed(BL13), and the width-direction acceleration a_(w) for whichlow-frequency components are suppressed (BL14) are used to analyze themotion of the vehicle 5. The motion analysis of the vehicle 5 isexecuted when an event is detected in the block BL2.

The motion analysis of the vehicle 5 includes computation of a passingduration taken for the vehicle 5 to enter and leave the floor slab 4 d,determination of stoppage of the vehicle 5 on the floor slab 4 d,determination of path changes of the vehicle 5 on the floor slab 4 d,and determination of the entering direction of the vehicle 5 into thefloor slab 4 d. The motion analysis of the vehicle 5 indicated by theblock BL20 is executed using the analysis unit 26 described below.

As indicated by the block BL21, the vertical-direction displacement ofthe floor slab 4 d which has been computed in the block BL12 is used tocompute the passing duration of the vehicle 5 on the floor slab 4 d. Thepassing duration computation indicated by the block BL21 is executedusing the passing duration computation unit 31 described below.

As indicated by the block BL22, the vertical-direction displacement ofthe floor slab 4 d which has been computed in the block BL12 and thewidth-direction acceleration a_(w) for which high-frequency componentshave been suppressed in the block BL13 are used to determine stoppage ofthe vehicle 5. The stoppage determination of the vehicle 5 indicated bythe block BL22 is executed using the stoppage determination unit 32described below.

As indicated by the block BL23, the width-direction acceleration a_(w)for which high-frequency components have been suppressed in the blockBL13 is used to determine the path change of the vehicle 5. The pathchange determination of the vehicle 5 indicated by the block BL23 isexecuted using the path change determination unit 33 described below.

As indicated by the block BL24, the width-direction acceleration a_(w)for which high-frequency components have been suppressed in the blockBL13 and the width-direction acceleration a_(w) for which low-frequencycomponents have been suppressed in the block BL14 are used to determinethe entering direction of the vehicle 5. The entering directiondetermination of the vehicle 5 indicated by the block BL24 is executedusing the entering direction determination unit 34 described below.

Description will continue with reference to FIG. 4. Thevertical-direction acceleration acquired using the acquisition unit 21is input to the event detection unit 22 (refer to the block BL1 in FIG.5). The event detection unit 22 computes the absolute value of the inputvertical-direction acceleration and computes the envelope curve (signal)of the computed absolute value.

FIG. 6 is a view illustrating an example of an envelope curve. For agraph G1 illustrated in FIG. 6, the horizontal axis indicates time, andthe vertical axis indicates acceleration.

A waveform W1 a illustrated in the graph G1 indicates thevertical-direction acceleration from which an offset input to the eventdetection unit 22 has been removed. A waveform W1 b indicated by adashed line indicates the vertical-direction acceleration of which theabsolute value has been computed using the event detection unit 22. Thatis, the waveform W1 b is a waveform obtained by inverting negativeportions in the waveform W1 a to be positive. A waveform W1 c indicatesan envelope curve computed using the event detection unit 22.

The vertical-direction acceleration acquired using the acquisition unit21 is input to the event detection unit 22 without passing through theintrinsic resonance-blocking filter unit 23 and the vehiclecomponent-blocking filter unit 25, and the event detection unit 22computes the envelope curve of the vertical-direction acceleration.

The event detection unit 22 determines whether or not the amplitude ofthe computed envelope curve exceeds a predetermined threshold value. Theevent detection unit 22 detects an event in a case in which theamplitude of the computed envelope curve exceeds a predeterminedthreshold value (refer to the block BL2 in FIG. 5).

Description will continue with reference to FIG. 4. Thevertical-direction acceleration and the width-direction accelerationwhich have been acquired using the acquisition unit 21 are input to theintrinsic resonance-blocking filter unit 23 (refer to the blocks BL11and BL 13 in FIG. 5). The intrinsic resonance-blocking filter unit 23suppresses the intrinsic resonance frequency of the floor slab 4 d whichis included in the vertical-direction acceleration and thewidth-direction acceleration which have been input.

FIG. 7 is a view illustrating an example of the frequencycharacteristics of acceleration when the vehicle 5 passes through thefloor slab 4 d. For a graph G2 illustrated in FIG. 7, the horizontalaxis indicates frequency, and the vertical axis indicates power spectrumdensity. The length of the floor slab 4 d at which the frequencycharacteristics of acceleration are measured is “30 m”.

A waveform W2 a illustrated in the graph G2 indicates the frequencycharacteristics of the acceleration in the x-axis direction (refer toFIG. 2) of the acceleration sensor 2 mounted on the side surface 4 da ofthe floor slab 4 d. A waveform W2 b indicates the frequencycharacteristics of the acceleration in the y-axis direction of theacceleration sensor 2. A waveform W2 c indicates the frequencycharacteristics of the acceleration in the z-axis direction of theacceleration sensor 2.

As illustrated in the graph G2, the acceleration in the respective axeshas peaks in a range of approximately “5 Hz to 30 Hz”. Several peaksnear at “10 Hz” are considered to result from the intrinsic resonance ofthe floor slab 4 d.

The acceleration illustrated in the graph G2 in a range of “0.1 Hz to 1Hz” is regarded as acceleration generated by the deformation of thefloor slab 4 d which is caused by the passing of the vehicle 5 at aspeed in a range of “3 m/s to 17 m/s” which are assumed as speedsnecessary for the vehicle 5 to pass through the floor slab 4 d. This isbecause, for example, when the speed of the vehicle 5 passing throughthe floor slab 4 d is set in a range of “3 m/s to 17 m/s”, the vibrationcycle (a duration in which the floor slab bends downwards and thenreturns to the original location) generated by the deformation of thefloor slab 4 d which is caused by the passing of the vehicle 5 isconsidered to reach “10 s to 1.8 s” (0.1 Hz to 0.6 Hz) which isapproximately equal to the passing duration of the vehicle 5.

Frequency components that are lower than “0.1 Hz” are considered toresult from the long-term cyclic changes of the floor slab 4 d due tothe environment such as temperature and wind, the normal micro-motion(environmental vibrations) of land surfaces, the 1/f fluctuation noiseof sensors, and the like.

According to what has been described above, the frequencycharacteristics of the acceleration of the floor slab 4 d are generallyclassified into a high pass part including the intrinsic resonancefrequency of the floor slab 4 d and a low pass part including thefrequencies of acceleration generated by the passing of the vehicle 5.For example, the frequency characteristics of the accelerationillustrated in the graph G2 include the intrinsic resonance frequency ofthe floor slab 4 d at frequencies higher than at least “1 Hz” andinclude the frequency components of acceleration generated by thepassing of the vehicle 5 which is caused by the deformation of the floorslab 4 d at frequencies of “1 Hz” or lower.

The intrinsic resonance frequency of the floor slab 4 d varies dependingon the structure, material, and the like of the bridge 4. In addition,the frequency components of acceleration generated by the deformation ofthe floor slab 4 d which is caused by the passing of the vehicle 5 varydepending on the length of the floor slab 4 d and the imaginary speed ofthe vehicle 5 passing through the floor slab 4 d.

As described below, the analysis unit 26 analyzes the motion of thevehicle 5 on the floor slab 4 d. Therefore, the intrinsic resonancefrequency components of the floor slab 4 d which are included in thevertical-direction acceleration and the width-direction acceleration areinformation not necessary to analyze the motion of the vehicle 5(although described below, in the determination of the enteringdirection, the intrinsic resonance frequency components are also used(BL14 in FIG. 5)). Therefore, the intrinsic resonance-blocking filterunit 23 suppresses the intrinsic resonance frequency components of thefloor slab 4 d which are included in the vertical-direction accelerationand the width-direction acceleration.

As described above, the frequency characteristics of the acceleration ofthe floor slab 4 d are generally classified into a high pass partincluding the intrinsic resonance frequency of the floor slab 4 d and alow pass part including the frequencies of acceleration generated by thepassing of the vehicle 5. Therefore, the intrinsic resonance-blockingfilter unit 23 is constituted of, for example, a low pass filter (LPF).The cut-off frequency of LPF is set to be higher than the accelerationfrequency generated by the deformation of the floor slab 4 d which iscaused by the passing of the vehicle 5 and is set to be lower than theintrinsic resonance frequency of the floor slab 4 d. For example, in thecase of the example of the frequency characteristics illustrated in thegraph G2 of FIG. 7, the cut-off frequency is set to “1 Hz”. In such acase, for vertical-direction acceleration and width-directionacceleration which pass through the intrinsic resonance-blocking filterunit 23, the intrinsic resonance frequency components of the floor slab4 d are blocked, and the frequency components of acceleration generatedby the deformation of the floor slab 4 d which is caused by the passingof the vehicle 5 pass through.

The intrinsic resonance-blocking filter unit 23 is desirably constitutedof a Bessel filter so as to prevent information that waveforms ofacceleration have from being lost.

In addition, as described above, the intrinsic resonance frequency ofthe floor slab 4 d varies depending on the kind or structure of thebridge 4 and, in some cases, appears at near the frequency ofacceleration generated by the deformation of the floor slab 4 d which iscaused by the passing of the vehicle 5. For example, in the graph G2 ofFIG. 7, there are cases in which the intrinsic resonance frequencyappears at near 3 Hz. In this case, the cut-off frequency of the filteris decreased or the filter order is increased so that the intrinsicresonance frequency is sufficiently suppressed.

Description will continue with reference to FIG. 4. Thevertical-direction acceleration for which the intrinsic resonancefrequency components of the floor slab 4 d are suppressed is input tothe displacement computation unit 24 using the intrinsicresonance-blocking filter unit 23 (refer to the block BL12 in FIG. 5).The displacement computation unit 24 computes the vertical-directiondisplacement (x-axis direction displacement) of the floor slab 4 d fromthe input vertical-direction acceleration. For example, the displacementcomputation unit 24 computes the vertical-direction displacement of thefloor slab 4 d by integrating the vertical-direction acceleration twice.

The width-direction acceleration acquired using the acquisition unit 21is input to the vehicle component-blocking filter unit 25 (refer to theblock BL14 in FIG. 5). The vehicle component-blocking filter unit 25suppresses the acceleration components of the floor slab 4 d generatedby the passing of the vehicle 5 which are included in the inputwidth-direction acceleration.

As described above, the frequency characteristics of the acceleration ofthe floor slab 4 d are generally classified into a high pass partincluding the intrinsic resonance frequency of the floor slab 4 d and alow pass part including the deformation components of the floor slabgenerated by the passing of the vehicle 5. Therefore, the vehiclecomponent-blocking filter unit 25 is constituted of, for example, a highpass filter (HPF). The cut-off frequency of HPF is set to be higher thanthe acceleration frequency generated by the deformation of the floorslab 4 d which is caused by the passing of the vehicle 5 and is set tobe lower than the intrinsic resonance frequency of the floor slab 4 d.For example, in the case of the example of the frequency characteristicsillustrated in the graph G2 of FIG. 7, the cut-off frequency is set to“1 Hz”. In such a case, for width-direction acceleration which passesthrough the vehicle component-blocking filter unit 25, the frequencycomponents of acceleration generated by the deformation of the floorslab 4 d which is caused by the passing of the vehicle 5 are blocked,and the intrinsic resonance frequency components of the floor slab 4 dpass through.

The vehicle component-blocking filter unit 25 is desirably constitutedof a Bessel filter so as to prevent information that waveforms ofwidth-direction acceleration have from being lost.

In addition, as described above, the intrinsic resonance frequency ofthe floor slab 4 d varies depending on the kind or structure of thebridge 4 and, in some cases, appears at near the frequency ofacceleration generated by the deformation of the floor slab 4 d which iscaused by the passing of the vehicle 5. For example, in the graph G2 ofFIG. 7, there are cases in which the intrinsic resonance frequencyappears in a range of 1 to 10 Hz. In this case, the cut-off frequency ofthe filter is decreased or the filter order is increased so thatacceleration frequency components generated by the deformation of thefloor slab 4 d which is caused by the passing of the vehicle 5 aresufficiently suppressed.

When the event detection unit 22 detects an event, the analysis unit 26analyzes the motion of the vehicle 5 moving on the floor slab 4 d on thebasis of at least one of the vertical-direction displacement which iscomputed from the vertical-direction acceleration and thewidth-direction acceleration (refer to the block BL20 in FIG. 5). Asillustrated in FIG. 4, the analysis unit 26 has a passing durationcomputation unit 31, the stoppage determination unit 32, the path changedetermination unit 33, and an entering direction determination unit 34.

Before the description of the respective units in the analysis unit 26,the width-direction acceleration and the vertical-direction displacementof the floor slab 4 d which are generated by the passing of the vehicle5 will be described.

FIG. 8 is a first view illustrating the width-direction acceleration andthe vertical-direction displacement of the floor slab 4 d which aregenerated by the passing of the vehicle 5.

FIG. 8 illustrates a section of the floor slab 4 d and the main beams 4f to 4 i illustrated in FIG. 2. In addition, FIG. 8 illustrates theacceleration sensor 2 mounted on the floor slab 4 d.

A model M1 of a dot-dashed line illustrated in FIG. 8 indicates thelocation of the floor slab 4 d when the vehicle 5 does not pass throughon the floor slab 4 d. A model M2 of a solid line indicates the locationof the floor slab 4 d when the vehicle 5 passes through a traffic laneindicated by an arrow A1 a on the floor slab 4 d (for example, thevehicle runs toward you from behind the paper).

When the vehicle 5 runs along the traffic lane indicated by the arrow A1a on the floor slab 4 d, the floor slab 4 d is inclined due to the loadof the vehicle 5 so that the right-side end in the drawing is placed tobe vertically lower than the left-side end as indicated by the model M2.Therefore, the z axis of the acceleration sensor 2 mounted on the floorslab 4 d is inclined downwards from the horizontal direction asindicated by a dashed arrow A1 b. The width-direction acceleration is acomponent of the acceleration of gravity due to the slope of the floorslab 4 d in the width direction.

FIG. 9 is a second view illustrating the width-direction accelerationand the vertical-direction displacement of the floor slab 4 d which aregenerated by the passing of the vehicle 5. In FIG. 9, the samecomponents as in FIG. 8 are given the same reference sign. A model M3 ofa solid line illustrated in FIG. 9 indicates the location of the floorslab 4 d when the vehicle 5 passes through a traffic lane indicated byan arrow A2 a on the floor slab 4 d (for example, the vehicle runstoward behind the paper from you).

When the vehicle 5 runs along the traffic lane indicated by the arrow A2a on the floor slab 4 d, the floor slab 4 d is inclined due to the loadof the vehicle 5 so that the left-side end is placed to be verticallylower than the right-side end as indicated by the model M3. Therefore,the z axis of the acceleration sensor 2 mounted on the floor slab 4 d isinclined upwards from the horizontal direction as indicated by a dashedarrow A2 b.

The z axis of the acceleration sensor 2 is oriented downwards or upwardswith respect to the horizontal direction depending on the location ofthe vehicle 5 running on the floor slab 4 d as indicated by the dashedarrow A1 b in FIG. 8 and the dashed arrow A2 b in FIG. 9. That is, thewidth-direction acceleration that is output from the acceleration sensor2 has a sign which changes depending on the location (running trafficlane) of the vehicle 5 running on the floor slab 4 d. For example, in acase in which the vehicle 5 runs along the traffic lane indicated by thearrow A1 a in FIG. 8, the sign of the width-direction acceleration thatis output from the acceleration sensor 2 becomes negative. On the otherhand, in a case in which the vehicle 5 runs along the traffic laneindicated by the arrow A2 a in FIG. 9, the sign of the width-directionacceleration that is output from the acceleration sensor 2 becomespositive.

In addition, for the z axis of the acceleration sensor 2, the angle ofthe slope with respect to the horizontal direction changes due to thevehicle weight of the vehicle 5 passing through on the floor slab 4 d.For example, in FIG. 8, as the vehicle weight of the vehicle 5 runningalong the traffic lane indicated by the arrow A1 a increases, the angleof the dashed arrow A1 b inclined downwards with respect to thehorizontal direction increases. In addition, in FIG. 9, as the vehicleweight of the vehicle 5 running along the traffic lane indicated by thearrow A2 a increases, the angle of the dashed arrow A1 b inclinedupwards with respect to the horizontal direction increases.

When the vehicle 5 passes through on the floor slab 4 d, thevertical-direction displacement of the floor slab 4 d has any one of apositive sign and a negative sign. For example, when the vehicle 5passes through on the floor slab 4 d, the floor slab 4 d bends downwardas indicated by an arrow A1 c in FIG. 8 and an arrow A2 c in FIG. 9regardless of the running traffic lane of the vehicle 5. Therefore, forexample, when a vertically upward orientation is regarded as positive,the vertical-direction displacement has a negative value.

In addition, the degree of the vertical-direction displacement isproportional to the vehicle weight of the vehicle 5. For example, as thevehicle weight of the vehicle increases, the floor slab 4 d bendsdownwards more significantly, and the vertical-direction displacementincreases.

The respective units in the analysis unit 26 will be described. First,the passing duration computation unit 31 will be described. Thevertical-direction displacement of the floor slab 4 d which has beencomputed using the displacement computation unit 24 is input to thepassing duration computation unit 31 (refer to the block BL21 in FIG.5). The passing duration computation unit 31 computes the passingduration of the vehicle 5 passing through the floor slab 4 d on thebasis of the input vertical-direction displacement.

FIG. 10 is a first view illustrating the passing duration of the vehicle5. For a graph G3 illustrated in FIG. 10, the horizontal axis indicatestime, and the vertical axis indicates displacement. A waveform W3 in thegraph G3 indicates the vertical-direction displacement of the floor slab4 d which is generated by an event.

When the vehicle 5 enters the floor slab 4 d and runs toward the centralportion (the location on which the acceleration sensor 2 is mounted),the crest value of the vertical-direction displacement graduallyincreases. When the vehicle 5 has run in the central portion, the crestvalue of the vertical-direction displacement is maximized. In addition,when the vehicle 5 runs away from the central portion, the crest valueof the vertical-direction displacement gradually decreases, and, whenthe vehicle leaves the floor slab 4 d, the crest value reaches almost“0”. Therefore, the passing duration of the vehicle 5 passing throughthe floor slab 4 d can be estimated from the wave amplitude of thewaveform W3 indicated by an arrow A3.

That is, the passing duration computation unit 31 computes the passingduration of the vehicle 5 passing through the floor slab 4 d from thewave amplitude of vertical-direction displacement. That is, the passingduration computation unit 31 turns the wave amplitude duration of thevertical-direction displacement into the passing duration of the vehicle5 passing through the floor slab 4 d. In the example of the graph G3,the crest value of the vertical-direction displacement is maximized at atime t₀. Therefore, it is found that the vehicle 5 passes through thecentral portion of the floor slab 4 d at the time t₀.

The wave amplitude of the vertical-direction displacement is regardedas, for example, a difference between a time t₁ at which thevertical-direction displacement reaches an extreme value h₁ before atime t₀ at which the vertical-direction displacement is minimized duringan event and a time t₂ at which the vertical-direction displacementreaches an extreme value h₂ after a time t₀ at which thevertical-direction displacement is minimized. The definition of the waveamplitude of the vertical-direction displacement is not limited thereto.For example, a difference between a time t₃₁ at which thevertical-direction displacement generated by an event goes below apredetermined threshold value h₃ and a time t₃₂ at which thevertical-direction displacement goes above a predetermined thresholdvalue h₃ may be regarded as the wave amplitude of the vertical-directiondisplacement.

As long as the passing duration of the vehicle 5 passing through thefloor slab 4 d can be computed, it is also possible to estimate thespeed of the vehicle 5. For example, the passing duration computationunit 31 is capable of computing the speed of the vehicle 5 passingthrough the floor slab 4 d by dividing the length of the floor slab 4 dby the computed passing duration.

The passing duration computation unit 31 may divide the wave amplitudeof the vertical-direction displacement generated by an event intomultiple sections and compute the passing duration of the vehicle 5 onthe floor slab 4 d for each of the divided sections. For example, thepassing duration computation unit 31 may compute a passing durationtaken for the vehicle 5 to enter the floor slab 4 d and pass through thecentral portion of the floor slab 4 d and a passing duration taken forthe vehicle to run from the central portion of the floor slab 4 d andexit the floor slab 4 d.

FIG. 11 is a second view illustrating the passing duration of thevehicle 5. For a graph G4 illustrated in FIG. 11, the horizontal axisindicates time, and the vertical axis indicates displacement. A waveformW4 in the graph G4 indicates the vertical-direction displacement of thefloor slab 4 d which is generated by an event.

The passing duration computation unit 31 divides the wave amplitude ofthe vertical-direction displacement generated by an event into multiplesections. For example, as indicated by arrows A4 a and A4 b, the passingduration computation unit 31 divides the wave amplitude using the timet₀ at which the crest value of the vertical-direction displacement ismaximized as a boundary. The definition of the wave amplitude of thevertical-direction displacement generated by an event is the same as thedefinition of the wave amplitude described in FIG. 10.

When the wave amplitude is divided, the passing duration computationunit 31 computes the passing duration of the vehicle 5 on the floor slab4 d for each of the divided wave amplitudes. For example, the time t₀ inthe graph G4 is a time at which the vehicle 5 has passed through thecentral portion of the floor slab 4 d as described above. Therefore, ina case in which the wave amplitude is divided using the time t₀ at whichthe crest value of the vertical-direction displacement is maximized as aboundary, the passing duration computation unit 31 computes a passingduration taken for the vehicle 5 to enter the floor slab 4 d and passthrough the central portion of the floor slab 4 d and a passing durationtaken for the vehicle to run from the central portion of the floor slab4 d and exit the floor slab 4 d.

As described above, when the wave amplitude is divided, it is foundwhether or not the vehicle 5 changes the speed on the floor slab 4 d.For example, in the example of the graph G4, as indicated by the arrowsA4 a and A4 b, the passing duration taken for the vehicle to run fromthe central portion of the floor slab 4 d and exit the floor slab 4 dbecomes longer than the passing duration taken for the vehicle to enterthe floor slab 4 d and pass through the central portion and thus it isfound that the vehicle 5 decreases the speed in the central portion ofthe floor slab 4 d.

Next, the stoppage determination unit 32 will be described. Thevertical-direction displacement of the floor slab 4 d which is outputfrom the displacement computation unit 24 and the width-directionacceleration which is output from the intrinsic resonance-blockingfilter unit 23 are input to the stoppage determination unit 32 (refer tothe block BL22 in FIG. 5). The stoppage determination unit 32 determinesthe stoppage of the vehicle 5 on the floor slab 4 d on the basis of thevertical-direction displacement and the width-direction accelerationwhich have been input.

FIG. 12 is a view illustrating an example of width-directionacceleration and vertical-direction displacement in a case in which thevehicle 5 passes through on the floor slab 4 d without stopping. For agraph G5 illustrated in FIG. 12, the horizontal axis indicates time. Forthe graph G5, the left vertical axis indicates acceleration, and theright vertical axis indicates displacement.

A waveform W5 a in the graph G5 indicates an example of a temporalchange of width-direction displacement. A waveform W5 b in the graph G5indicates an example of a temporal change of vertical-directiondisplacement. If width-direction acceleration has a “positive” sign whenthe z axis of the acceleration sensor 2 is oriented upwards with respectto the horizontal direction, the waveform. 5 a indicates width-directionacceleration in a case in which the vehicle 5 runs along the trafficlane of the arrow A2 a illustrated in FIG. 9.

When the vehicle 5 enters the floor slab 4 d, the floor slab 4 d bendsdownwards due to the vehicle weight of the vehicle 5. Therefore,width-direction acceleration and vertical-direction acceleration(vertical-direction displacement) are generated in the floor slab 4 d.For example, the width-direction acceleration and the vertical-directiondisplacement in the graph G5 all change immediately after the time t₁(the width-direction acceleration increases, and the vertical-directiondisplacement decreases). Therefore, the time t₁ indicates a time atwhich the vehicle 5 enters the floor slab 4 d.

During the running of the vehicle 5 on the floor slab 4 d,width-direction acceleration and vertical-direction displacement arecontinuously generated in the floor slab 4 d. In addition, when thevehicle 5 leaves the floor slab 4 d, the vehicle weight of the vehicle 5is not applied to the floor slab 4 d any longer, and thus thewidth-direction acceleration and the vertical-direction displacementreach almost “0”. For example, a time t₂ indicates a time at which thevehicle 5 leaves the floor slab 4 d, and the width-directionacceleration and the vertical-direction displacement are almost “0” atthe time t₂ and later.

That is, in a case in which the vehicle 5 runs on the floor slab 4 dwithout stopping, width-direction acceleration and vertical-directiondisplacement are generated in the floor slab 4 d while the vehicle 5runs on the floor slab 4 d. Therefore, in a case in which the vehicle 5runs on the floor slab 4 d without stopping, the wave amplitude ofwidth-direction acceleration and the wave amplitude ofvertical-direction displacement become almost identical to each other.

The wave amplitude of width-direction acceleration generated by an eventis considered to be, for example, a difference between a time t₁ atwhich the crest value of the width-direction acceleration begins toincrease and a time t₂ at which the crest value of the width-directionacceleration stops to decrease. The definition of the wave amplitude isnot limited thereto. For example, a difference between a time at whichthe crest value of width-direction acceleration generated by an eventexceeds a predetermined threshold value h₁ and a time at which the crestvalue turns to be below a predetermined threshold value h₁ may beregarded as the wave amplitude.

FIG. 13 is a view illustrating an example of width-directionacceleration and vertical-direction displacement in a case in which thevehicle 5 stops on the floor slab 4 d. For a graph G6 illustrated inFIG. 13, the horizontal axis indicates time. For a graph G6, the leftvertical axis indicates acceleration, and the right vertical axisindicates displacement.

A waveform W6 a in the graph G6 indicates an example of a temporalchange of width-direction acceleration. A waveform W6 b in the graph G6indicates an example of a temporal change of vertical-directiondisplacement.

When the vehicle 5 enters the floor slab 4 d, the floor slab 4 d bendsdownwards due to the vehicle weight of the vehicle 5. Therefore,width-direction acceleration and vertical-direction acceleration(vertical-direction displacement) are generated in the floor slab 4 d.For example, the width-direction acceleration and the vertical-directiondisplacement in the graph G6 all change immediately after the time t₁(the width-direction acceleration increases, and the vertical-directiondisplacement decreases). Therefore, the time t₁ indicates a time atwhich the vehicle 5 enters the floor slab 4 d.

Even when the vehicle 5 stops on the floor slab 4 d, width-directionacceleration is continuously generated until the vehicle 5 leaves thefloor slab 4 d. For example, a time t₄ indicates a time at which thevehicle 5 leaves the floor slab 4 d, and width-direction acceleration iscontinuously generated between the time t₁ at which the vehicle 5 entersthe floor slab 4 d and the time t₄ at which the vehicle leaves the floorslab.

On the other hand, when the vehicle 5 stops on the floor slab 4 d, thevertical-direction displacement returns to zero (0) to a certain extentas indicated by the waveform W6 b. For example, when the peak issuppressed as illustrated at the time t₂, later (for example, a timet₃), the vertical-direction displacement returns to zero to a certainextent. The time t₂ at which the vertical-direction displacement peaksis a time at which the vehicle 5 stops.

That is, in a case in which the vehicle 5 stops on the floor slab 4 d,width-direction acceleration is continuously generated until the vehicle5 leaves as in a case in which the vehicle 5 does not stop on the floorslab 4 d. On the other hand, the vertical-direction displacement returnsto almost zero after the vehicle 5 stops unlike a case in which thevehicle 5 does not stop on the floor slab 4 d. That is, in a case inwhich the vehicle 5 stops on the floor slab 4 d, the wave amplitude ofwidth-direction acceleration and the wave amplitude ofvertical-direction displacement are different from each other. Forexample, the wave amplitude of the width-direction accelerationindicated by an arrow A5 a in the graph G6 and the wave amplitude of thevertical-direction displacement indicated by an arrow A5 b aresignificantly different from each other.

According to what has been described above, the stoppage determinationunit 32 determines the stoppage of the vehicle 5 on the floor slab 4 don the basis of the wave amplitude of width-direction acceleration andthe wave amplitude of vertical-direction displacement. For example, in acase in which the wave amplitude of width-direction acceleration islarger by a predetermined value than the wave amplitude ofvertical-direction displacement, the stoppage determination unit 32determines the stoppage of the vehicle 5 on the floor slab 4 d.Specifically, in a case in which the wave amplitude of width-directionacceleration is twice or larger the wave amplitude of vertical-directiondisplacement, the stoppage determination unit 32 determines the stoppageof the vehicle 5 on the floor slab 4 d.

As described above, the time t₂ at which the vertical-directiondisplacement peaks indicates a time at which the vehicle 5 stops on thefloor slab 4 d. In addition, the time t₄ at which the crest value of thewidth-direction acceleration stops to decrease (a time at which the waveamplitude of the width-direction acceleration ends) indicates a time atwhich the vehicle 5 leaves the floor slab 4 d. Therefore, the stoppagedetermination unit 32 is capable of computing (estimating) a differencebetween the time t₂ at which the vertical-direction displacement peaksand the time t₄ at which the crest value of the width-directionacceleration stops to decrease as a stoppage time at which the vehicle 5stops on the floor slab 4 d.

Next, the path change determination unit 33 will be described.Width-direction acceleration that is output from the intrinsicresonance-blocking filter unit 23 is input to the path changedetermination unit 33 (refer to the block BL23 in FIG. 5). The pathchange determination unit 33 determines the path changes of the vehicle5 on the floor slab 4 d on the basis of the input width-directionacceleration.

FIG. 14 is a first view illustrating a path change of the vehicle 5 onthe floor slab 4 d. In FIG. 14, the floor slab 4 d illustrated in FIG. 2and the acceleration sensor 2 mounted on the side surface 4 da of thefloor slab 4 d are illustrated. As indicated by an arrow A6 in FIG. 14,the vehicle 5 is considered to run beyond the central portion of thefloor slab 4 d in a direction intersecting at right angles a regulationdirection (for example, a central traffic lane) and change the path froma traffic lane far from the acceleration sensor 2 to a traffic laneclose to the acceleration sensor 2.

FIG. 15 is a view illustrating a change in the width-directionacceleration during the path change of FIG. 14. For a graph G7illustrated in FIG. 15, the horizontal axis indicates time, and thevertical axis indicates acceleration. A waveform W7 in the graph G7indicates width-direction acceleration of the floor slab 4 d which isgenerated by an event.

Before the path change, the vehicle 5 runs along the traffic lane farfrom the acceleration sensor 2. Therefore, width-direction accelerationbeing generated in the floor slab 4 d continuously has a positive crestvalue (for example, refer to FIG. 9) as indicated by an arrow A1 a. Inaddition, as the vehicle 5 changes the path toward the traffic laneclose to the acceleration sensor 2, width-direction acceleration beinggenerated in the floor slab 4 d continuously has a negative crest value(for example, refer to FIG. 8) as indicated by an arrow A1 b. Inaddition, when the vehicle 5 leaves the floor slab 4 d, width-directionacceleration reaches almost “0”.

The crest value of the width-direction acceleration is regarded as, forexample, a difference between a value h₁ at which the crest value of thewidth-direction acceleration before the event is almost constant andvalues h₂ and h₃ at which the crest value of the width-directionacceleration during the event peaks. The value h₁ may be set to “0”. Thedefinition of the crest value of the width-direction acceleration is notlimited thereto.

FIG. 16 is a second view illustrating a path change of the vehicle 5 onthe floor slab 4 d. In FIG. 16, the floor slab 4 d illustrated in FIG. 2and the acceleration sensor 2 mounted on the side surface 4 da of thefloor slab 4 d are illustrated. As indicated by an arrow A8 in FIG. 16,the vehicle 5 is considered to change the path without running beyondthe central portion of the floor slab 4 d in a direction intersecting atright angles the regulation direction.

FIG. 17 is a view illustrating a change in the width-directionacceleration during the path change of FIG. 16. For a graph G8illustrated in FIG. 17, the horizontal axis indicates time, and thevertical axis indicates acceleration. A waveform W8 in the graph G8indicates width-direction acceleration of the floor slab 4 d which isgenerated by an event.

Before the path change, the vehicle 5 runs along the traffic lane farfrom the acceleration sensor 2. Therefore, width-direction accelerationbeing generated in the floor slab 4 d continuously has a positive crestvalue as indicated by an arrow A9 a.

After that, the vehicle 5 changes the path toward the traffic lane closeto the acceleration sensor 2 but does not run beyond the central portionof the floor slab 4 d in a direction intersecting at right angles theregulation direction. Therefore, for width-direction accelerationgenerated in the floor slab 4 d, as indicated by the arrow. A9 b, thesign thereof remains positive, and the crest value decreases. Inaddition, when the vehicle 5 leaves the floor slab 4 d, thewidth-direction acceleration reaches almost “0”.

As described using FIGS. 14 to 17, when the vehicle 5 changes the pathon the floor slab 4 d, the sign of the crest value of thewidth-direction acceleration changes. In addition, when the vehicle 5changes the path on the floor slab 4 d, the crest value of thewidth-direction acceleration changes. In addition, the path changedetermination unit 33 determines the path change of the vehicle 5 on thefloor slab 4 d on the basis of the crest value and sign ofwidth-direction acceleration.

Specifically, in the example of the waveform W7 in FIG. 15, the sign ofthe crest value changes as indicated by the arrows A1 a and 7 b.Therefore, the path change determination unit 33 determines that thevehicle 5 changes the path on the floor slab 4 d. In addition, in theexample of the waveform W8 in FIG. 17, a first crest value continues asindicated by the arrow A9 a, and then a second crest value which issmaller than the first crest value and has the same sign as the firstcrest value continues as indicated by the arrow A9 b. Therefore, thepath change determination unit 33 determines that the vehicle 5 changesthe path on the floor slab 4 d.

The path change determination unit 33 is capable of determining how thevehicle 5 changes the path using changes in the sign of the crest valueand the degree of the crest value of the width-direction acceleration.For example, in a case in which the vehicle 5 changes the path from thetraffic lane close to the acceleration sensor 2 to the far traffic laneby running beyond the central portion of the floor slab 4 d in adirection intersecting at right angles the regulation direction, for thewidth-direction acceleration, a negative crest value continues in thebeginning, and then a positive crest value continues. In addition, in acase in which the vehicle 5 changes the path from the traffic lane closeto the acceleration sensor 2 to the traffic lane far from theacceleration sensor 2 without running beyond the central portion of thefloor slab 4 d in a direction intersecting at right angles theregulation direction, the crest value decreases while the sign of thewidth-direction acceleration remains negative. As described above, thesign and degree of the crest value of the width-direction accelerationchange due to the path change of the vehicle 5, and thus the path changedetermination unit 33 is capable of determining the changed pathdirections of the vehicle 5.

In addition, the definition of the crest value is the same as thedefinition described using FIG. 15.

Next, the entering direction determination unit 34 will be described.Width-direction acceleration that is output from the intrinsicresonance-blocking filter unit 23 and width-direction acceleration thatis output from the vehicle component-blocking filter unit 25 are inputto the entering direction determination unit 34 (refer to the block BL24in FIG. 5). The entering direction determination unit computes theabsolute value of the width-direction acceleration that is output fromthe vehicle component-blocking filter unit 25 and computes the envelopecurve of the computed absolute value. In addition, the enteringdirection determination unit 34 determines the entering direction of thevehicle 5 into the floor slab 4 d on the basis of the computed envelopecurve and the width-direction acceleration that is output from theintrinsic resonance-blocking filter unit 23.

FIG. 18 is a view illustrating the entering direction of the vehicle 5into the floor slab 4 d. In FIG. 18, the floor slabs 4 d and 4 eillustrated in FIG. 2 and the acceleration sensor 2 mounted on the sidesurface 4 da of the floor slab 4 d are illustrated.

As the entering direction of the vehicle 5 into the floor slab 4 d,there are a direction in which the vehicle enters the floor slab 4 dwithout passing through the adjacent floor slab 4 e (for example,directly from roads) as indicated by an arrow A10 a and a direction inwhich the vehicle enters the floor slab 4 d from the adjacent floor slab4 e as indicated by an arrow A10 b.

FIG. 19 is a view illustrating width-direction acceleration and anenvelope curve thereof in a case in which the vehicle 5 directly entersthe floor slab 4 d on which the acceleration sensor 2 is mounted. For agraph G9 a illustrated in FIG. 19, the horizontal axis indicates time,and the vertical axis indicates acceleration. For a graph G9 b, thehorizontal axis indicates time, and the vertical axis indicatesamplitude.

A waveform W9 a in the graph G9 a indicates width-direction accelerationthat is output from the intrinsic resonance-blocking filter unit 23. Awaveform W9 b in the graph G9 b indicates an envelope curve that iscomputed using the entering direction determination unit 34.

When the vehicle 5 enters the floor slab 4 d from a direction indicatedby the arrow A10 a in FIG. 18, the floor slab 4 d bends downwards due tothe vehicle weight of the vehicle 5, and acceleration is generated inthe width direction. The waveform W9 a from the time t₁ to the time t₂indicates width-direction acceleration while the vehicle 5 enters thefloor slab 4 d from the direction indicated by the arrow A10 a in FIG.18 and leaves the floor slab 4 d.

In a case in which the vehicle 5 enters the floor slab 4 d from thedirection indicated by the arrow A10 a in FIG. 18, when the vehicleleaves the floor slab 4 d, the vehicle enters the adjacent floor slab 4e on which the acceleration sensor 2 is not mounted. When the vehicle 5enters the adjacent floor slab 4 e, the floor slab 4 d does not benddownwards due to the vehicle weight of the vehicle 5, and thuswidth-direction acceleration generated by the vehicle weight of thevehicle 5 as indicated by the waveform W9 a from the time t₁ to the timet-₂ is not generated after the time t₂.

However, while the vehicle 5 runs in the floor slab 4 e adjacent to thefloor slab 4 d, vibrations of the floor slab 4 e which are generated bythe running of the vehicle 5 are transferred to the floor slab 4 d. Thevibrations transferred from the adjacent floor slab 4 e to the floorslab 4 d are detected using the acceleration sensor 2 mounted on thefloor slab 4 d and appear in a form of width-direction accelerationindicated by the waveform W9 a from the time t₂ to the time t₃. Thewidth-direction acceleration indicated by the waveform W9 a from thetime t₂ to the time t₃ is considered to result from the intrinsicresonance of the floor slab 4 d which is generated by the vibrationstransferred from the floor slab 4 e.

The time t₃ indicates a time at which the vehicle 5 leaves the floorslab 4 e. After the time t₃, the width-direction acceleration reachesalmost “0”.

The waveform W9 a indicates the width-direction acceleration that isoutput from the intrinsic resonance-blocking filter unit 23. That is,the waveform W9 a indicates width-direction acceleration for whichhigh-frequency components due to the intrinsic resonance of the floorslab 4 d are suppressed. Therefore, in the floor slab 4 d,width-direction acceleration that is greater than the width-directionacceleration indicated by the waveform W9 a from the time t₂ to the timet₃ is generated.

As described above, the entering direction determination unit 34computes the absolute value of width-direction acceleration that isoutput from the vehicle component-blocking filter unit 25 and computesthe envelope curve of the computed absolute value. In thewidth-direction acceleration that is output from the vehiclecomponent-blocking filter unit 25, acceleration components generated bythe passing of the vehicle 5 are suppressed, and acceleration componentsdue to the intrinsic resonance of the floor slab 4 d pass through.Therefore, the envelope curve computed using the entering directiondetermination unit 34 becomes the envelope curve of acceleration basedon at least the intrinsic resonance of the floor slab 4 d, and it ispossible to detect the passing of the vehicle 5 on the floor slab 4 eadjacent to the floor slab 4 d in a form of a large amplitude of theenvelope curve of width-direction acceleration as indicated by thewaveform W9 b from the time t₂ to the time t₃.

That is, in a case in which the vehicle 5 runs from the floor slab 4 don which the acceleration sensor 2 is mounted to the floor slab 4 e onwhich the acceleration sensor 2 is not mounted, the waveform W9 b has apredetermined amplitude while the vehicle 5 runs in the adjacent floorslab 4 e (from the time t₂ to the time t₃) even after the crest value ofthe waveform W9 a becomes small (after the time t₂).

FIG. 20 is a view illustrating width-direction acceleration and anenvelope curve thereof in a case in which the vehicle 5 enters from theadjacent floor slab 4 e on which the acceleration sensor 2 is notmounted. For a graph G10 a illustrated in FIG. 20, the horizontal axisindicates time, and the vertical axis indicates acceleration. For agraph G10 b, the horizontal axis indicates time, and the vertical axisindicates amplitude.

A waveform W10 a in the graph G10 a indicates width-directionacceleration that is output from the intrinsic resonance-blocking filterunit 23. A waveform W10 b in the graph G10 b indicates an envelope curvethat is computed using the entering direction determination unit 34.

When the vehicle 5 enters the floor slab 4 e from a direction indicatedby the arrow A10 b in FIG. 18, vibrations of the floor slab 4 e whichare generated by the running of the vehicle 5 are transferred to thefloor slab 4 d. The vibrations transferred from the floor slab 4 e tothe floor slab 4 d are detected using the acceleration sensor 2 mountedon the floor slab 4 d and appear in a form of width-directionacceleration indicated by the waveform W10 a from the time t₁ to thetime t₂. The width-direction acceleration indicated by the waveform W10a from the time t₁ to the time t₂ is considered to result from theintrinsic resonance of the floor slab 4 d which is generated by thevibrations transferred from the floor slab 4 e.

In a case in which the vehicle 5 enters the floor slab 4 e from thedirection indicated by the arrow A10 b in FIG. 18, when the vehicleleaves the floor slab 4 e, the vehicle enters the floor slab 4 d onwhich the acceleration sensor 2 is mounted. When the vehicle 5 entersthe floor slab 4 d, the floor slab 4 d bends downwards due to thevehicle weight of the vehicle 5. Therefore, width-direction accelerationgenerated by the vehicle weight of the vehicle 5 as indicated by thewaveform W10 a from the time t₂ to the time t₃ is generated in the floorslab 4 d.

The time t₃ indicates a time at which the vehicle 5 leaves the floorslab 4 d. After the time t₃, the width-direction acceleration reachesalmost “0”.

As described above, the entering direction determination unit 34computes the absolute value of width-direction acceleration that isoutput from the vehicle component-blocking filter unit 25 and computesthe envelope curve of the computed absolute value. In thewidth-direction acceleration that is output from the vehiclecomponent-blocking filter unit 25, acceleration components generated bythe passing of the vehicle 5 are suppressed, and acceleration componentsdue to the intrinsic resonance of the floor slab 4 d pass through.Therefore, the envelope curve computed by the entering directiondetermination unit 34 becomes the envelope curve of acceleration basedon at least the intrinsic resonance of the floor slab 4 d, and it ispossible to detect the passing of the vehicle 5 on the floor slab 4 eadjacent to the floor slab 4 d in a form of a large amplitude of anenvelope curve of width-direction acceleration as indicated by thewaveform W10 b from the time t₂ to the time t₃.

That is, in a case in which the vehicle 5 runs from the floor slab 4 eon which the acceleration sensor 2 is not mounted to the floor slab 4 don which the acceleration sensor 2 is mounted, the waveform W10 b has apredetermined amplitude even before the crest value of the waveform W10a becomes large (before the time t₂) due to the entering of the vehicle5 into the floor slab 4 e.

According to what has been described above, the entering directiondetermination unit 34 is capable of determining the entering directionof the vehicle 5 into the floor slab 4 d on the basis of the appearancetime of the envelope curve with respect to the width-directionacceleration that is output from the intrinsic resonance-blocking filterunit 23. For example, the entering direction determination unit 34 iscapable of determining the entering direction on the basis of whether anenvelope curve appears before width-direction acceleration appears or anenvelope curve appears even after width-direction acceleration does notappear any longer.

For example, as illustrated in FIG. 19, in a case in which an envelopecurve (the waveform W9 b) of width-direction acceleration appears evenafter width-direction acceleration due to an event (width-directionacceleration of the waveform W9 a from the time t₁ to the time t₂) doesnot appear any longer (after the time t₂), the entering directiondetermination unit 34 determines that the vehicle 5 enters from adirection of the arrow A10 a in FIG. 18. Specifically, in a case inwhich an envelope curve of width-direction acceleration has an amplitudewith a predetermined duration and a predetermined threshold value orhigher even after width-direction acceleration due to an event does notappear any longer, the entering direction determination unit 34determines that the vehicle 5 enters the floor slab 4 d in a directionopposite to the adjacent floor slab 4 e.

In addition, as illustrated in FIG. 20, in a case in which an envelopecurve (the waveform W10 b) of width-direction acceleration appearsbefore width-direction acceleration due to an event (width-directionacceleration of the waveform W10 a from the time t₂ to the time t₃) isgenerated (before the time t₂), the entering direction determinationunit 34 determines that the vehicle 5 enters from a direction of thearrow A10 b in FIG. 18. Specifically, in a case in which an envelopecurve of width-direction acceleration has an amplitude with apredetermined duration and a predetermined threshold value or higherbefore width-direction acceleration due to an event is generated, theentering direction determination unit 34 determines that the vehicle 5enters the floor slab 4 d from the adjacent floor slab 4 e.

Hereinafter, the operation of the measurement instrument 1 will bedescribed using a flowchart.

FIG. 21 is a flowchart illustrating an operation example of themeasurement instrument 1. The measurement instrument 1 repeatedlyexecutes the processes in the flowchart illustrated in FIG. 21, forexample, at a timing at which the acceleration sensor 2 outputsacceleration.

First, the acquisition unit 21 acquires acceleration of the accelerationsensor 2 which has been sent using the communication unit 12 (Step S1).

Next, the event detection unit 22 detects an event on the basis ofvertical-direction acceleration included in the acceleration acquired inStep S1 (Step S2). In a case in which an event is detected (“Yes” inS2), the event detection unit 22 transfers the process to Step S3. In acase in which no event is detected (“No” in S2), the event detectionunit 22 terminates the process of the flowchart. In addition, themeasurement instrument 1 executes the process of Step S1 again at atiming at which the acceleration sensor 2 outputs acceleration.

In Step S2, in a case in which an event is determined to be detected(“Yes” in S2), the intrinsic resonance-blocking filter unit 23suppresses the intrinsic resonance frequency of the floor slab 4 d whichis included in the width-direction acceleration and thevertical-direction acceleration (Step S3).

Next, the displacement computation unit 24 computes thevertical-direction displacement of the floor slab 4 d from thevertical-direction acceleration for which the intrinsic resonancefrequency of the floor slab 4 d is suppressed in Step S3 (Step S4). Forexample, the displacement computation unit 24 computes thevertical-direction displacement of the floor slab 4 d by integrating thevertical-direction acceleration for which the intrinsic resonancefrequency of the floor slab 4 d is suppressed twice.

Next, the passing duration computation unit 31 computes the passingduration of the vehicle 5 that has passed through the floor slab 4 d(Step S5). For example, the passing duration computation unit 31computes the passing duration of the vehicle 5 that has passed throughthe floor slab 4 d on the basis of the wave amplitude duration of thevertical-direction displacement of the floor slab 4 d which has beencomputed in Step S4 (for example, refer to FIGS. 10 and 11).

Next, the stoppage determination unit 32 determines the stoppage of thevehicle 5 on the floor slab 4 d (Step S6). For example, the stoppagedetermination unit 32 determines the stoppage of the vehicle 5 on thefloor slab 4 d on the basis of the wave amplitude of the width-directionacceleration for which the intrinsic resonance components of the floorslab 4 d is suppressed in Step S3 and the wave amplitude of thevertical-direction displacement of the floor slab 4 d which has beencomputed in Step S4 (for example, refer to FIG. 13).

Next, the path change determination unit 33 determines the path changesof the vehicle 5 on the floor slab 4 d (Step S7). For example, the pathchange determination unit 33 determines the path changes of the vehicle5 on the floor slab 4 d on the basis of changes in the amplitude of thewidth-direction acceleration for which the intrinsic resonancecomponents of the floor slab 4 d is suppressed in Step S3 (for example,refer to FIGS. 15 and 17).

Next, the vehicle component-blocking filter unit 25 suppressesacceleration components generated by the bending of the floor slabcaused by the passing of the vehicle 5 which are included in thewidth-direction acceleration (Step S8).

Next, the entering direction determination unit 34 determines theentering direction of the vehicle 5 into the floor slab 4 d (Step S9).For example, the entering direction determination unit 34 determines theentering direction of the vehicle 5 into the floor slab 4 d on the basisof the width-direction acceleration for which the intrinsic resonancecomponents of the floor slab 4 d is suppressed in Step S3 and theenvelope curve of the width-direction acceleration for which thefrequency component generated by the bending of the floor slab caused bythe passing of the vehicle 5 in Step S8 is suppressed (for example,refer to FIGS. 19 and 20). When the process of Step S9 is terminated,the measurement instrument 1 terminates the process of the flowchart andexecutes the process of Step S1 again at a timing at which theacceleration sensor 2 outputs acceleration.

The processing sequence of the measurement instrument 1 is not limitedto the flowchart of FIG. 21. For example, the processes of Steps S5, S6,S7, and S9 are not limited to the sequence in the flowchart of FIG. 21.In addition, the processes of Steps S5, S6, S7, and S9 may be executedin parallel. However, the filtering process of Step S8 is executed atleast before the entering direction determination process of Step S9.

As described above, the acquisition unit 21 in the measurementinstrument 1 acquires at least one of the vertical-directionacceleration and the width-direction acceleration of the floor slab 4 dfrom the acceleration sensor 2 provided in the floor slab 4 d on whichthe vehicle 5 passes through. In addition, the analysis unit 26 analyzesthe motion of the vehicle 5 passing through on the floor slab 4 d on thebasis of at least one of the vertical-direction acceleration and thewidth-direction acceleration acquired by the acquisition unit 21. Insuch a case, the measurement instrument 1 analyzes the motion of movingobjects on structures using small-size and simple system constitutionsand is capable of reducing costs or saving efforts for installation ofsensors. For example, the measurement instrument 1 does not need toanalyze the motion of the vehicle 5 using a variety of sensors and iscapable of reducing costs. In addition, the measurement instrument 1 iscapable of analyzing the motion of the vehicle 5 from at least oneacceleration sensor 2 and saves efforts for the installation of sensorson the floor slab 4 d.

In addition, the intrinsic resonance-blocking filter unit 23 suppressesthe intrinsic resonance frequency of the floor slab 4 d which isincluded in the width-direction acceleration and the vertical-directionacceleration and has no relationship with the analysis of the motion ofthe vehicle 5. In such a case, the analysis unit 26 is capable ofappropriately analyzing the motion of the vehicle 5.

In addition, the vehicle component-blocking filter unit 25 suppressesacceleration components due to the vehicle 5 which are included in thewidth-direction acceleration and allows the passing of the intrinsicresonance frequency of the floor slab 4 d. In such a case, the analysisunit 26 is capable of appropriately determining the entering directionof the vehicle 5.

In addition, the analysis unit 26 analyzes the motion of the vehicle 5in accordance with event detection in the event detection unit 22. Insuch a case, the analysis unit 26 is capable of reducing processingloads.

The display unit 14 may output the results of event detection detectedusing the event detection unit 22, the analysis results of the motion ofthe vehicle 5 which are analyzed using the analysis unit 26, and thelike to display devices. In such a case, users are able to learn, forexample, the motion of the vehicle 5 passing through on the floor slab 4d.

In addition, in the above description, the analysis of the motion of thevehicle 5 has been described for an example of one traffic lane on asingle side, but the invention is not limited thereto. For example, themeasurement instrument 1 is also capable of analyzing the motion of thevehicle 5 on floor slabs not including traffic lanes. In addition, themeasurement instrument 1 is also capable of analyzing the motion of thevehicle 5 on floor slabs including two or more traffic lanes on a singleside.

In addition, in a case in which the floor slab 4 d includes one trafficlane on a single side, the measurement instrument 1 is capable ofdetermining whether or not the vehicle 5 or the like runs along thetraffic lane from the sign of the width-direction acceleration. Forexample, in a case in which the width-direction acceleration has a“negative” sign, the measurement instrument 1 is capable of determiningthat the vehicle 5 passes through a traffic lane far from theacceleration sensor 2 (for example, refer to FIG. 8). In addition, in acase in which the width-direction acceleration has a “positive” sign,the measurement instrument 1 is capable of determining that the vehicle5 passes through a traffic lane close to the acceleration sensor 2 (forexample, refer to FIG. 9).

In addition, in a case in which the floor slab 4 d includes one trafficlane on a single side and a traffic lane along which the vehicle 5 runshas been determined between right and left traffic lanes, themeasurement instrument 1 is capable of determining the enteringdirection of the vehicle 5 from the sign of the width-directionacceleration. For example, it is assumed that the vehicle 5 needs tokeep to the left. In this case, in a case in which the width-directionacceleration has a “negative” sign, the measurement instrument 1 iscapable of determining that, for example, the vehicle 5 enters from adirection of the adjacent floor slab 4 e. In addition, in a case inwhich the width-direction acceleration has a “positive” sign, themeasurement instrument 1 is capable of determining that, for example,the vehicle 5 enters from a direction opposite to the adjacent floorslab 4 e. In a case in which the floor slab 4 d includes one trafficlane on a single side and a traffic lane along which the vehicle 5 runshas been determined between right and left traffic lanes, themeasurement instrument 1 is capable of determining the enteringdirection of the vehicle 5 even when the adjacent floor slab 4 e is notpresent (for example, only the floor slab 4 d is present).

In addition, the analysis unit 26 computes the passing duration of thevehicle 5 on the basis of the vertical-direction displacement, but maycompute the passing duration of the vehicle 5 on the basis of thewidth-direction acceleration. For example, the analysis unit 26 maycompute the passing duration of the vehicle 5 on the basis of the waveamplitude of the width-direction acceleration.

In addition, the analysis unit 26 may compare the respective waveamplitudes of the waveforms of the vertical-direction displacement andthe width-direction acceleration and compute the passing duration. Forexample, the analysis unit 26 may compute a duration during which thewave amplitudes of the vertical-direction displacement and thewidth-direction acceleration superimpose each other as the passingduration.

Second Embodiment

In a second embodiment, the preservation (storage) of width-directionacceleration and vertical-direction displacement when an event isgenerated will be described.

FIG. 22 is a view illustrating an example of the functional blocks ofthe measurement instrument 1 according to a second embodiment. In FIG.22, the same components as in FIG. 4 are given the same reference signand will not be described again. As illustrated in FIG. 22, themeasurement instrument 1 has an acceleration waveform acquisition unit41 and a displacement waveform acquisition unit 42.

In a case in which an event is detected using the event detection unit22, the acceleration waveform acquisition unit 41 acquires thecharacteristic information of the waveform of width-directionacceleration generated by the event. Although described below in detail,the characteristic information is about, for example, the crest value,wave amplitude, and waveform coefficient of the width-directionacceleration and a time at which the vehicle 5 passes through theacceleration sensor 2. The acceleration waveform acquisition unit 41stores the acquired characteristic information of the width-directionacceleration in the storage unit 13.

The waveform of the width-direction acceleration generated by the eventhas an approximately trapezoidal shape. Therefore, even when not all thedata of the width-direction acceleration generated by the event isstored in the storage unit 13, it is possible to execute the approximaterestoration of the waveform of the width-direction acceleration in atrapezoidal shape by storing the characteristic information in thestorage unit 13. That is, the analysis unit 26 is capable of restoringtrapezoidal width-direction acceleration from the characteristicinformation stored in the storage unit 13 and is capable of analyzingthe motion of the vehicle 5, for example, even later on according tousers' request and the like.

FIG. 23 is a view illustrating the characteristic information of thewidth-direction acceleration and the restoration of the width-directionacceleration from the characteristic information. For graphs G21 and G22illustrated in FIG. 23, the horizontal axis indicates time, and thevertical axis indicates acceleration.

A waveform W21 illustrated in the graph G21 indicates width-directionacceleration generated by the event. A waveform W22 illustrated in thegraph G22 indicates width-direction acceleration restored from thecharacteristic information stored in the storage unit 13.

The acceleration waveform acquisition unit 41 acquires thecharacteristic information of the waveform W21. For example, theacceleration waveform acquisition unit 41 acquires the crest valueindicated by an arrow A21 a in the graph G21 and the wave amplitudeindicated by an arrow A21 b. In addition, the acceleration waveformacquisition unit 41 acquires the waveform coefficient indicated by anarrow A21 c (the slope of the increasing width-direction acceleration)and the waveform coefficient indicated by an arrow A21 d (the slope ofthe decreasing width-direction acceleration). In addition, theacceleration waveform acquisition unit 41 acquires a time t₀ at whichthe vehicle 5 passes through the acceleration sensor 2.

The crest value of the width-direction acceleration is regarded as, forexample, a difference between a value h₁₁ at which the crest value ofthe width-direction acceleration before the event is almost constant anda value h₁₂ at which the crest value of the width-direction accelerationduring the event peaks and is expressed as the following expression.

Crest value=h ₁₂ −h ₁₁

The value h₁₁ may be set to “0”.

The wave amplitude is regarded as, for example, a difference between atime t₁₁ at which the crest value of the width-direction accelerationbegins to increase and a time t₁₄ at which the crest value of thewidth-direction acceleration stops to decrease and is expressed as thefollowing expression.

Wave amplitude=t ₁₄ −t ₁₁

The waveform coefficient of the increasing width-direction accelerationis regarded as, for example, the slope of the width-directionacceleration obtained from the time t₁₁ at which the crest value of thewidth-direction acceleration begins to increase, a time t₁₂ at which thewidth-direction acceleration reaches the value h₁₂, and the crest valueand is expressed as the following expression.

Waveform coefficient=(h ₁₂ −h ₁₁)/(t ₁₂ −t ₁₁)

The waveform coefficient of the decreasing width-direction accelerationis regarded as, for example, the slope of the width-directionacceleration obtained from a time t₁₃ at which the crest value of thewidth-direction acceleration during the event begins to decrease, thetime t₁₄ at which the width-direction acceleration reaches the valueh₁₁, and the crest value and is expressed as the following expression.

Waveform coefficient=(h ₁₁ −h ₁₂)/(t ₁₄ −t ₁₃)

The time t₀ at which the vehicle 5 passes through the accelerationsensor 2 is regarded as, for example, a time at which the crest value ofthe vertical-direction displacement is maximized (for example, refer tothe time t₀ in FIGS. 10 and 11).

The definition of the characteristic information is not limited thereto.For example, the crest value may be regarded as the maximum value of thecrest value of the width-direction acceleration generated by the event.In addition, the wave amplitude may be regarded as a difference betweena time at which the crest value of the width-direction accelerationgenerated by the event exceeds a predetermined threshold value h₁₃ and atime at which the crest value turns to be below the predeterminedthreshold value h₁₃.

The acceleration waveform acquisition unit 41 stores the acquiredcharacteristic information in the storage unit 13. In such a case, theanalysis unit 26 is capable of restoring the width-directionacceleration generated by the event as a trapezoidal waveform asindicated by the waveform W22 from the characteristic information storedin the storage unit 13. For example, the analysis unit 26 increases thewidth-direction acceleration up to the crest value “h₁₂−h₁₁” using thewaveform coefficient of the increasing width-direction acceleration andthe time t₁₁ which is a time traced back from the time t₀ by half thewave amplitude as a starting point. In addition, the analysis unit 26increases the width-direction acceleration up to the crest value“h₁₂−h₁₁” using the waveform coefficient of the decreasingwidth-direction acceleration and the time t₁₄ which is a time tracedback from the time t₀ by half the wave amplitude as a starting point. Inaddition, the analysis unit 26 restores the width-direction accelerationgenerated by the event by connecting two points at times at which thewidth-direction acceleration is increased up to the crest value.

The acceleration waveform acquisition unit 41 is also capable ofacquiring the waveform W7 illustrated in FIG. 15 or the characteristicinformation of the waveform W9 b illustrated in FIG. 19 and storing themin the storage unit 13. For example, the acceleration waveformacquisition unit 41 captures the waveform W7 or the waveform W9 b as awaveform of a combination of two trapezoids, acquires characteristicinformation, and stores the characteristic information in the storageunit 13.

Description will continue with reference to FIG. 22. In a case in whichan event is detected using the event detection unit 22, the displacementwaveform acquisition unit 42 acquires the characteristic information ofthe waveform of vertical-direction displacement generated by the event.Although described below in detail, the characteristic information isabout, for example, the crest value and wave amplitude of thevertical-direction displacement and a time at which the vehicle 5 passesthrough the acceleration sensor 2. The displacement waveform acquisitionunit 42 stores the acquired characteristic information of thevertical-direction displacement in the storage unit 13.

The waveform of the vertical-direction displacement generated by theevent is approximated using Expression (1) below.

$\begin{matrix}{{u(t)} = {h_{u} \cdot a^{- {(\frac{t - t_{0}}{w_{u}})}^{2}}}} & (1)\end{matrix}$

In Expression (1), “h_(u)” represents the crest value of thevertical-direction displacement, and “w_(u)” represents the waveamplitude of the vertical-direction displacement. “t₀” represents thetime at which the vehicle 5 passes through the acceleration sensor 2and, for example, a time at which the vertical-direction displacementduring the event reaches the minimum value. “a” represents the waveformcoefficient and a constant determined by the floor slab 4 d.

Therefore, even when not all the data of the vertical-directiondisplacement generated by the event is stored in the storage unit 13, itis possible to restore the waveform of the vertical-directiondisplacement from Expression (1) by storing the characteristicinformation in the storage unit 13. That is, the analysis unit 26 iscapable of restoring the vertical-direction displacement from thecharacteristic information stored in the storage unit 13 and is capableof analyzing the motion of the vehicle 5, for example, even later onaccording to users' request and the like.

FIG. 24 is a view illustrating the characteristic information of thevertical-direction displacement and the restoration of thevertical-direction displacement from the characteristic information. Forgraphs G23 and G24 illustrated in FIG. 24, the horizontal axis indicatestime, and the vertical axis indicates displacement.

A waveform W23 illustrated in the graph G23 indicates thevertical-direction displacement generated by the event. A waveform W24illustrated in the graph G24 indicates the vertical-directiondisplacement restored from the characteristic information stored in thestorage unit 13.

The displacement waveform acquisition unit 42 acquires thecharacteristic information of the waveform W23. For example, thedisplacement waveform acquisition unit 42 acquires the crest valueindicated by an arrow A22 a in the graph G23 and the wave amplitudeindicated by an arrow A22 b. In addition, the displacement waveformacquisition unit 42 acquires the time t₀ at which the vehicle 5 passesthrough the acceleration sensor 2.

The crest value of the vertical-direction displacement is regarded as,for example, a difference between an extreme value h₂ which is a largerone of an extreme value h₁ of the vertical-direction displacement beforethe time t₀ at which the vertical-direction displacement during theevent is minimized and the extreme value h₂ of the vertical-directiondisplacement after the time t₀ at which the vertical-directiondisplacement is minimized and the minimum value h₀ of thevertical-direction displacement during the event. The definition of thecrest value of the vertical-direction displacement is not limitedthereto, and, for example, the minimum value h₀ of thevertical-direction displacement during the event may be regarded as thecrest value. The wave amplitude of the vertical-direction displacementis the same as the wave amplitude described using FIG. 10 and will notbe described again.

The displacement waveform acquisition unit 42 stores the acquiredcharacteristic information in the storage unit 13. In such a case, theanalysis unit 26 is capable of restoring the vertical-directiondisplacement generated by the event as a waveform as indicated by thewaveform W24 using the characteristic information stored in the storageunit 13 and Expression (1). For example, the analysis unit 26substitutes the crest value “h_(u)” stored in the storage unit 13, thewave amplitude “w_(u)”, and the time “t₀” at which the vehicle 5 passesthrough the acceleration sensor 2 into Expression (1). In such a case,the analysis unit 26 is capable of restoring the vertical-directiondisplacement generated by the event and is capable of analyzing themotion of the vehicle 5, for example, even later on according to users'request and the like.

The waveform coefficient “a” in Expression (1) is computed in advancefor every floor slab 4 d. For example, the actual measurement values ofthe crest value and wave amplitude of the vertical-directiondisplacement and the time at which the vehicle 5 passes through theacceleration sensor 2 are substituted into Expression (1). In addition,the waveform coefficient “a” is computed in advance so that the waveformin Expression (1) is most approximated to the waveform of actualvertical-direction displacement by comparing the waveform indicated byExpression (1) and the waveform of actual vertical-directiondisplacement when actual values are measured.

The displacement waveform acquisition unit 42 is also capable ofacquiring the asymmetric waveform W4 as illustrated in FIG. 11 andstoring the waveform in the storage unit 13. For example, theacceleration waveform acquisition unit 41 divides the waveform W4 intotwo waveforms using the time t₀ as a boundary, respectively acquires thecharacteristic information thereof, and stores the characteristicinformation in the storage unit 13.

The flowchart of the measurement instrument 1 according to the secondembodiment is identical to that in FIG. 21. However, at least after theprocess of Step S2, a storage process of the characteristic informationof the waveforms is executed using the acceleration waveform acquisitionunit 41 and the displacement waveform acquisition unit 42.

In the measurement instrument 1 according to the second embodiment, theprocesses of vehicle motion analysis of Steps S5 to S9 may not beexecuted. The processes of vehicle motion analysis may be executedaccording to, for example, user's request and the like. For example,when a user makes an analysis request, the analysis unit 26 acquires thecharacteristic information stored in the storage unit 13 and restoreshorizontal-direction acceleration and vertical-direction displacementwhich are generated by the event from the acquired characteristicinformation. In addition, the analysis unit 26 may analyze the motion ofthe vehicle 5 from the horizontal-direction acceleration andvertical-direction displacement which have been restored.

As described above, the acceleration waveform acquisition unit 41acquires the characteristic information of the waveform of thewidth-direction acceleration generated by the event. In addition, thedisplacement waveform acquisition unit 42 acquires the characteristicinformation of the waveform of the vertical-direction displacementgenerated by the event. In such a case, the storage unit 13 is capableof reducing storage capacity.

In addition, the analysis unit 26 is capable of restoring thewidth-direction acceleration or the vertical-direction displacement fromthe characteristic information stored in the storage unit 13 and is thuscapable of analyzing the motion of the vehicle 5 on the floor slab 4 d,for example, even later on according to users' request and the like.

The acceleration waveform acquisition unit 41 may acquire thecharacteristic information of the width-direction acceleration that isoutput from the acceleration sensor 2 and store the characteristicinformation in the storage unit 13 or may acquire the characteristicinformation of the width-direction acceleration that has been filteredusing the intrinsic resonance-blocking filter unit 23 and the vehiclecomponent-blocking filter unit 25 and store the characteristicinformation in the storage unit 13. In addition, the accelerationwaveform acquisition unit 41 may acquire the characteristic informationof the width-direction acceleration that has been filtered using theintrinsic resonance-blocking filter unit 23 and the vehiclecomponent-blocking filter unit 25 and store the characteristicinformation in the storage unit 13.

Third Embodiment

The acquisition unit 21 may acquire the travelling-directionacceleration (y-axis direction acceleration) of the floor slab 4 d whichis output from the acceleration sensor 2. In addition, the analysis unit26 may analyze the motion of the vehicle 5 on the basis of thetravelling-direction acceleration acquired using the acquisition unit21.

FIG. 25 is a view illustrating travelling-direction acceleration of afloor slab according to a third embodiment. FIG. 25 illustrates thefloor slab 4 d seen from the horizontal direction. In addition, FIG. 25illustrates the acceleration sensor 2 mounted on the floor slab 4 d.

A waveform W31 of a solid line illustrated in FIG. 25 indicates thebending of the floor slab 4 d when the vehicle 5 passes through the leftside on the center (the acceleration sensor 2) of the floor slab 4 d inFIG. 25. A waveform W32 of a dashed line indicates the bending of thefloor slab 4 d when the vehicle 5 passes through the center of the floorslab 4 d in FIG. 25. A waveform W33 of a dot-dashed line indicates thebending of the floor slab 4 d when the vehicle 5 passes through theright side on the center of the floor slab 4 d in FIG. 25.

FIG. 26 is a view illustrating a temporal change of travelling-directionacceleration. For graphs G31 and G32 illustrated in FIG. 26, thehorizontal axis indicates time, and the vertical axis indicatesacceleration.

A waveform W41 in the graph G31 indicates a change in thetravelling-direction acceleration when the vehicle 5 passes through onthe floor slab 4 d from the left side to the right side in FIG. 25. Awaveform W42 in the graph G32 indicates a change in thetravelling-direction acceleration when the vehicle 5 passes through onthe floor slab 4 d from the right side to the left side in FIG. 25. Inthe graphs G31 and G32, when the y axis of the acceleration sensor 2 isoriented upward with respect to the horizontal direction, the sign ofthe travelling-direction acceleration is set to be “positive”.

A case in which the vehicle 5 enters the floor slab 4 d through the leftside and leaves the floor slab through the right side in FIG. 25 will beconsidered. When the vehicle 5 runs toward the center from the left endof the floor slab 4 d, the floor slab 4 d bends as indicated by thewaveform W31 in FIG. 25. Therefore, the y axis of the accelerationsensor 2 is oriented upwards with respect to the horizontal directionand has a “positive” value. Subsequently, when the vehicle 5 passesthrough the center of the floor slab 4 d, the floor slab 4 d bends asindicated by the waveform W32 in FIG. 25. Therefore, the y axis of theacceleration sensor 2 is oriented along the horizontal direction and hasa “0” value. Subsequently, when the vehicle 5 runs toward the right endfrom the center of the floor slab 4 d, the floor slab 4 d bends asindicated by the waveform W33 in FIG. 25. Therefore, the y axis of theacceleration sensor 2 is oriented downwards with respect to thehorizontal direction and has a “negative” value. That is, in a case inwhich the vehicle 5 enters the floor slab 4 d through the left side andleaves the floor slab through the right side, the travelling-directionacceleration changes as indicated by the waveform W41.

A case in which the vehicle 5 enters the floor slab 4 d through theright side and leaves the floor slab through the left side in FIG. 25will be considered. When the vehicle 5 runs toward the center from theright end of the floor slab 4 d, the floor slab 4 d bends as indicatedby the waveform W33 in FIG. 25. Therefore, the y axis of theacceleration sensor is oriented downwards with respect to the horizontaldirection and has a “negative” value. Subsequently, when the vehicle 5passes through the center of the floor slab 4 d, the floor slab 4 dbends as indicated by the waveform W32 in FIG. 25. Therefore, the y axisof the acceleration sensor 2 is oriented along the horizontal directionand has a “0” value. Subsequently, when the vehicle 5 runs toward theleft end from the center of the floor slab 4 d, the floor slab 4 d bendsas indicated by the waveform W31 in FIG. 25. Therefore, the y axis ofthe acceleration sensor 2 is oriented upwards with respect to thehorizontal direction and has a “positive” value. That is, in a case inwhich the vehicle 5 enters the floor slab 4 d through the right side andleaves the floor slab through the left side, the travelling-directionacceleration changes as indicated by the waveform W42.

As indicated by the waveforms W41 and W42, the sign of thetravelling-direction acceleration changes depending on the enteringdirection of the vehicle 5 into the floor slab 4 d. Therefore, theanalysis unit 26 is capable of analyzing the entering direction of thevehicle 5 into the floor slab 4 d on the basis of the sign of thetravelling-direction acceleration.

In addition, the wave amplitude of the travelling-direction accelerationchanges depending on the passing duration of the vehicle 5 on the floorslab 4 d. For example, as the passing duration of the vehicle 5 on thefloor slab 4 d increases, the wave amplitude between the crest andtrough or the trough and crest of the travelling-direction accelerationincreases. Therefore, the analysis unit 26 is capable of analyzing thepassing duration of the vehicle 5 on the floor slab 4 d on the basis ofthe wave amplitude of the travelling-direction acceleration.

As described above, the analysis unit 26 is capable of analyzing themotion of the vehicle 5 on the basis of travelling-directionacceleration.

Hitherto, the invention has been described using embodiments, but thefunctional constitution of the measurement instrument has beenclassified in accordance with the main processing contents in order tofacilitate the understanding of the constitution of the measurementinstrument. The method or name of the classification of constituentelements is not limited by the invention of the present application. Theconstitution of the measurement instrument can also be classified into alarger number of constituent elements in accordance with processingcontents. In addition, the constitution can also be classified so that asingle constituent element executes more processes. In addition, thenumber of kinds of hardware used to execute the processes of therespective constituent elements may be one or multiple.

In addition, the technical scope of the invention is not limited to thescopes described in the above-described embodiments. It is clear topersons in the art that a variety of changes or improvements can beadded to the embodiments. In addition, it is clear from the scope of theappended claim that aspects obtained by adding the above-describedchanges or improvements to the embodiments can also be included in thetechnical scope of the invention. In addition, the invention can also beprovided in a form of a measurement method, a program for measurementinstruments, or a storage medium in which the program is stored.

The entire disclosures of Japanese Patent Application No. 2015-196618,filed Oct. 2, 2015 and No. 2015-196615, filed Oct. 2, 2015 are expresslyincorporated by reference herein.

What is claimed is:
 1. A measurement instrument comprising: anacquisition unit that acquires width-direction acceleration of a surfaceof a structure on which a moving object moves from an accelerationsensor provided in the structure on which the moving object moves; andan analysis unit that analyzes motion of the moving object moving on thestructure on the basis of the width-direction acceleration.
 2. Themeasurement instrument according to claim 1, wherein the accelerationsensor is provided in an end portion of the structure which is parallelto a regulation direction of a moving direction regulation unit for themoving object which is provided in the structure and in a centralportion of the end portion in the regulation direction.
 3. Themeasurement instrument according to claim 1, wherein the acquisitionunit has a displacement computation unit that acquiresvertical-direction acceleration of the surface of the structure on whichthe moving object moves and computes vertical-direction displacement ofthe structure on the basis of the vertical-direction acceleration, andthe analysis unit computes a passing duration of the moving objectmoving on the structure on the basis of the vertical-directiondisplacement.
 4. The measurement instrument according to claim 3,wherein the analysis unit computes a passing duration of the movingobject on the basis of the wave amplitude of the vertical-directiondisplacement generated due to movement of the moving object on thestructure.
 5. The measurement instrument according to claim 4, whereinthe analysis unit divides the wave amplitude into multiple sections andcomputes the passing duration of the moving object moving on thestructure which corresponds to each of the sections.
 6. The measurementinstrument according to claim 1, wherein the acquisition unit has adisplacement computation unit which acquires the vertical-directionacceleration of the surface of the structure on which the moving objectmoves and computes the vertical-direction displacement of the structureon the basis of the vertical-direction acceleration, and the analysisunit determines stoppage of the moving object on the structure on thebasis of the width-direction acceleration and the vertical-directiondisplacement.
 7. The measurement instrument according to claim 6,wherein the analysis unit determines stoppage of the moving object onthe structure on the basis of a wave amplitude of the width-directionacceleration generated due to movement of the moving object on thestructure and a wave amplitude of the vertical-direction displacementgenerated due to movement of the moving object on the structure.
 8. Themeasurement instrument according to claim 7, wherein the analysis unitdetermines stoppage of the moving object in a case in which the waveamplitude of the width-direction acceleration is larger by apredetermined value than the wave amplitude of the vertical-directionacceleration.
 9. The measurement instrument according to claim 7,wherein the analysis unit computes a stoppage time of the moving objecton the structure on the basis of a peak time of the vertical-directiondisplacement and a time at which the wave amplitude of thewidth-direction acceleration is terminated.
 10. The measurementinstrument according to claim 1, wherein the analysis unit determinespath changes of the moving object on the structure on the basis of thewidth-direction acceleration.
 11. The measurement instrument accordingto claim 10, wherein the analysis unit determines path changes of themoving object on the basis of a degree and a sign of a crest value ofthe width-direction acceleration.
 12. The measurement instrumentaccording to claim 1, wherein the analysis unit determines an enteringdirection of the moving object into the structure on the basis of thewidth-direction acceleration and an envelope curve of thewidth-direction acceleration.
 13. The measurement instrument accordingto claim 12, wherein the analysis unit determines the entering directionof the moving object on the basis of the appearance time of the envelopecurve with respect to the width-direction acceleration.
 14. Themeasurement instrument according to claim 13, wherein the analysis unitdetermines the entering direction of the moving object on the basis ofwhether the envelope curve appears even before the width-directionacceleration appears or the envelope curve appears even after thewidth-direction acceleration does not appear any longer.
 15. Themeasurement instrument according to claim 12, further comprising: afilter unit that suppresses acceleration components which are includedin the width-direction acceleration that is computed by the envelopecurve and is generated due to movement of the moving object on thestructure.
 16. The measurement instrument according to claim 1, furthercomprising: an acceleration waveform acquisition unit that acquires andstores characteristic information of waveforms of the width-directionacceleration.
 17. The measurement instrument according to claim 1,wherein the acquisition unit has a displacement computation unit thatacquires vertical-direction acceleration of a surface of the structureon which the moving object moves and computes vertical-directiondisplacement of the structure on the basis of the vertical-directionacceleration and a displacement waveform acquisition unit that acquiresand stores characteristic information of waveforms of thevertical-direction displacement.
 18. The measurement instrumentaccording to claim 1, further comprising: an output unit that outputsanalysis results of motion of the moving object.
 19. The measurementinstrument according to claim 1, further comprising: a filter unit thatsuppresses intrinsic resonance frequency components which are includedin the width-direction acceleration and that the structure has.
 20. Themeasurement instrument according to claim 1, wherein the structure is abridge.
 21. The measurement instrument according to claim 1, wherein thewidth-direction acceleration is a component of an acceleration ofgravity due to a slope of the structure.
 22. The measurement instrumentaccording to claim 1, wherein the analysis unit computes a passingduration of the moving object moving on the structure on the basis ofthe width-direction acceleration.
 23. A measurement method comprising:acquiring width-direction acceleration from an acceleration sensorprovided in a structure on which a moving object moves; and analyzingmotion of the moving object moving on the structure on the basis of thewidth-direction acceleration.
 24. A measurement system comprising: anacceleration sensor provided in a structure on which a moving objectmoves; an acquisition unit that acquires width-direction accelerationthat is output from the acceleration sensor; and an analysis unit thatanalyzes motion of the moving object moving on the structure on thebasis of the width-direction acceleration.
 25. A recording mediumstoring a program commanding a measurement instrument to execute asequence, the sequence comprising: acquiring width-directionacceleration from an acceleration sensor provided in a structure onwhich a moving object moves; and analyzing motion of the moving objectmoving on the structure on the basis of the width-directionacceleration.